This invention relates to gas/liquid separators for use with respiratory gas analyzers, and more particularly, to gas/liquid separator including a liquid trap filter for removing liquid from a respiratory gas sample.
Respiratory gas analyzers monitor exhaled air from a patient. It has long been recognized that means must be provided for removing excess moisture from the exhaled air prior to analysis. One technique for removing excess moisture from respiratory gas samples utilizes the effects of surface tension and capillary action to separate water from gas samples. Known gas/liquid separators, or water traps, employing this technique include a separation chamber which has a geometrical configuration designed to draw water away from a gas sample outlet and direct the water to a collection chamber. Examples of such prior art water traps are disclosed in U.S. Pat. Nos. 4,579,568 and 4,713,095 to Ricciardelli. However, these prior art water traps can become filled, and the sample inlet line that conducts exhaled air to the water trap can become blocked with condensed moisture.
Another water trap, disclosed in U.S. Pat. No. 4,924,860, employs a separation chamber having a geometrical configuration similar to the one disclosed in U.S. Pat. No. 4,713,095. This water trap additionally includes self-sealing filters which positively seal the exit ports of the water trap in the event the water trap becomes over filled and can no longer perform its water trap function. In one embodiment, one self-sealing filter is disposed in a sample outlet conduit and a further self-seating filter is disposed in a vacuum conduit. The self-sealing filters comprise a porous matrix including means for rendering the porous matrix substantially non-porous when exposed to water, thereby blocking the exit ports of the water trap.